In a wireless local area network (usually referred to as wireless LAN), a terminal which is going to start accessing using the wireless LAN receives authentication from an access point before starting communication. At the time of this communication start, beacon signals transmitted by the access point at a predetermined time interval may be used. Namely, the access point transmits signal including an identifier referred to as SSID (Service Set IDentifier) as a beacon signal. The terminal side receives this SSID, and determines an access point to which the terminal asks for authentication.
In order to avoid connection from a random user, an access point does not transmit any beacon signals, and does not respond to a response request transmitted from a terminal side to any access points. Namely, the stealth mode is set to the access point. However, focusing on a problem that the SSID may be leaked even in the stealth mode if communication with an authorized terminal is intercepted, the Patent Document 1 discloses a technology to encrypt the SSID and set the leading 1 by to “0x00” to represent that the encryption is performed.